<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>05_流程控制</title>
</head>
<body>
<script>
    //1.顺序结构
    console.log('1');
    console.log('2');
    console.log('3');
    //2.分支结构
    let username = 'rose';
    if(!username){
        //alert('请输入用户名！')
    }else {
        //alert('欢迎'+username+'回归！')
    }
    //3.选择分支
    let gender = 10;
    switch (gender){
        case 1:
            console.log('男');
            break;
        case 0:
            console.log('女');
            break;
        default:
            console.log('未知')
    }
    //4.循环结构
    let names = ['张三','李四','王五'];
    for (let i = 0;i<names.length;i++){
        console.log(names[i]);
    }
    //如果用var定义循环变量i，循环结束后在此处仍能打印出i的值
    //但如果用let定义，就会报错：变量i不存在
    //console.log(i);

    //增强for循环
    //let n为每轮遍历取出的值 names是被遍历的数组
    for (let n of names){
        console.log(n);
    }
</script>
</body>
</html>